The invention relates to the methods and devices for control of motor-vehicle starters.
A motor-vehicle starter conventionally includes (FIG. 1) an electric motor M, a contactor 10, and a circuit 20 for control of this contactor 10.
The contactor 10 includes a coil B (or several) and a movable core driving a switch K. For further details, refer to document FR-A-2 795 884 filed on Jun. 28, 2000, and more particularly to FIG. 1 of it.
Hence, when the coil B is supplied with electricity, the starter switch actuated, for example, by the ignition key so much [sic] closed, the movable core is allowed to move and to act on a rod shackled elastically to a movable contact, conventionally plate-shaped and intended, at the end of travel, to come into contact with fixed, electrical power-supply terminals linked respectively to the positive terminal (+Bat) of the battery and to the electric motor M. The switch K therefore includes the movable contact and the terminals. When it is closed the motor M is supplied with power.
The control circuit 20 includes a transistor T1, placed in series with the coil B, as well as a microcontroller 25 for control of this transistor T1.
The contactor 10 therefore has a role of electrical switch between a source (the battery of the vehicle) and the motor M, and also a role as actuator for means of meshing between the motor M and the internal-combustion engine of the vehicle.
More precisely, as can be seen in FIG. 1 of the abovementioned document FR-A-2 795 884, the contactor 10 is installed above the motor M, being parallel to it.
The movable core is shackled to the upper extremity of a fork-shaped lever with an intervening spring called tooth-on-tooth spring.
The lower end of the lever is configured to act on an inertia-type drive including a hub, a pinion and a free wheel interposed between the pinion and the hub; the said free wheel comprising an outer cage-shaped part integral with the hub, an inner part integral with the pinion and rollers interposed between the inner and outer parts.
The pinion, when it is moved by the lever via the movable core, is intended to mesh with the starter ring of the internal-combustion engine of the motor vehicle, knowing that the hub of the inertia-type drive meshes with an output shaft configured to be driven directly or indirectly by the electric motor M.
Because of this second role of the contactor, and for reasons of wear on the core, it has proved to be necessary to avoid over-rapid movement of the latter.
In order to exert control over the kinematics of movement of the movable core and of the inertia-type drive, a variation in useful current strength in the coil B is chosen, especially by taking into account various mechanical parameters specific to the inertia-type drive in question, such as its inertia and the friction forces which it encounters during its advance movement from its rest position to its working position.
Account is also taken of the inertia and of the friction forces of the core.
By way of example, the mass of an inertia-type drive may vary from 1 to 4, depending on whether it is intended for a starter of a small private vehicle or a heavy-goods-vehicle starter. Similarly, the friction of an inertia-type drive is markedly greater for a sliding-pinion starter than for an ogive-type pinion starter.
It has been proposed, in the document FR-A-2 795 884, to supply the coil of the contactor with a variable, pulsed current, the variation in the duty cycle of which, and thus in the effective current in the course of time, depend [sic] on the parameters of the movable core.
Depending on the starter for which it is intended, the microcontroller 25 is programmed appropriately.
In practice, the microcontroller 25 is placed on an electronics card, and the cards often differ only in the programming of the microcontroller. The card is preferably mounted into the contactor 10 in the vicinity of the fixed core of the contactor 10 as described, for example, in the document EP-A-0 751 545 to which reference will be made for further details. The risks are therefore higher of confusing the cards and of equipping contactors, starters or vehicles with unsuitable cards by mistake.
Moreover, this type of mistake is difficult to identify once the card has been mounted into the contactor, and the latter mounted on the starter, given that the electronic circuits associated with the contactor are integrated into it.
One solution would be to have an electronic socket for diagnosis on the contactor. However, such a socket features a bulky connector. Moreover, this amounts to an expensive solution.
The invention proposes to overcome this drawback here, that is to say to make it possible easily and reliably to identify the type of programming of a contactor-control microcontroller, especially when it is already mounted onto the starter.
This object is achieved, according to the invention, by a method of supplying power to a motor-vehicle electric-starter contactor in which, on a circuit for supplying power to the contactor, an effective-power-supply signal is provided having a chosen profile, characterised in that, on the power-supply circuit, a supplementary signal is also provided having a shape which is chosen in order to facilitate the identification of the profile of the effective-power-supply signal.
The invention also proposes a device for supplying power to a motor-vehicle starter contactor, including a circuit for supplying power to the contactor and means for providing, on this circuit, an effective-power-supply signal having a chosen profile, characterised in that it also includes means for providing, on the power-supply circuit, a supplementary signal having a shape which is chosen in order to facilitate the identification of the chosen profile of the effective-power-supply signal.